phillips



H, "F ,"5 Martin earn r U 'oFfF HUGO PHILLIPS, or nYnnsviLLn, CALIFORNIA BAND SAW Application filed May 29,

This invention relates to improvements in band saws and pertains particularly to an improved method of tensioning a saw.

The primary object of the present inven- 5 tion is to provide a band saw which is so ten- I v sioned that the cracking of the saw at the back edge and at the gullets of the teeth'will be prevented.

Another object of the invention is to provide a band saw so tensioned that in addition to preventing the cracking or spreading of,

the saw at the front and rear edges the saw will be properly maintained in position upon its supporting pulleys.

The invention will be best understoodfroln a consideration of the following detailed de scription'taken in connection with the acconr.

panying drawing forming part of this specification, with the understanding, however, that the invention is not confined to any strict conformity with the showing of the drawing but may be changed or modified so long as such changes or modifications mark no material departure from the salientfeatures of the invention as expressed in the appended claims.

In the drawing: Figure 1 1s a View in cross-sectlon of a'saw constructed in accordance with the present inventlon and a portion of a supporting pulley therefor.

Figure 2 is a view similar to Figure 1 show-,

ing the alteration occuring in the cross-sectional design of the saw after a period of use. Figure 3 is a view in plan of a portion of i a bandsaw constructed in accordance with the present invention. 7 j 7 As is, of course, well known to those familiar with the art to which the present invention relates, band saws are tensioned before being placed into service and this-tensioningconsists in giving to the saw a transverse arouate contour which, in saws'of a width of fourfive foot circle. lVhen the saw is placed in service the rear edge bears firmly against the periphery of the supporting wheel while the front or toothed edge projects a slight distance beyond the adjacent corner of the Wheel. The drag to which thesaw is subteen inches, conforms to a segment of a forty- 1930. Seria1.I\ To.457,389.

jected when in use places a severe strain upon the rear edge. and upon the front edge at the gullets of the teeth and this results in a'cracking of the saw.

in carrying out my invention I provide a saw such as that indicated generallyby the numeral 1 which in additionto havingthe usual transversely arcuate contour imparted thereto in the manner shownisformed at the V rearjedgetq provide a reversely curved portion 2 which'formsa rounded inner face, 3 which rests upon the periphery of the pulley l over which theisaw passes so that the edge of the saw does not come into contact withlthe pulley fac w i I in addition to forming the reversely curv' d portion 2 adjacentthe rear edge'of the saw terminate the main are upon which the sa is formed in the usualtensioning process at the point 5 which, in a saw of a width of fourteen inches, com s within approximately oneiinchof the gullets 6 of the tech 7. At this point 5 a slight curve isforined r 'v'ers'el to the main tension curve of thesaw, or in other words the same as the curved port on 2- so that the under face is formed to provide a rounded tread 8 which rests upon the periphery of the pulley wheel atat the front edge thereof, in themanner shown;

, F mm the foregoing it will be seen that with a'saw constructed in accordance with my invention there are provided two surfaces which extendlongitudinally of the saw, which come into contact with the surface of the pulley 4 overwhich the saw passes, these surfaces being indicated by the numerals 3 and 8. As these rounded surfaces, which may be termed treads or tires, are disposed inwardly from the adjacent edges ofthe saw it will be apparent that a great deal of the strain norinally'borne the. edges of saws of the character at present in use and which results in cracking of these saws, will be relieved and thus practically eliminate the formation of edge cracks.

Another benefit derived from forming a saw in the manner described .is that the proper tension of the saw will be maintained for a longer period of time than in saws of the character. at present in use thus saving a great deal of bench Work in connection with the maintenance of saws in proper condition.

After running a saw for approximately three weeks it will be found that instead of 5 being tensioned to conform to the arc of a forty-five foot circle as when first placed upon the machine, the saw will have, tensioned itself to a point where it will conform substantially to the curvature of a thirtym five foot circle as illustrated in Figure 2 thus drawing the edges closer to the surface of the pulley. The saw may then be taken to the bench and given a light roll to restore it to the proper curve or tension thus restoring 15 the rounded front and rear curves or tires which contact with the surface of the supporting pulleys.

From the foregoing description it will be readily seen that by constructing a saw in 90 accordance with the present invention besides preventing contact of the edges of the saw with the pulley body and thus preventing the formation of cracks in the saw the saw will tend to tension itself on the wheel thus further 25 separating the periods when it will be necessary for the saw filer to remove the saw to the work bench for retensioning.

Having thus described my invention, what I claim is:

an 1. An improved band saw having a transverse tension curve, formed to provide at points inwardly of each edge thereof a pulley engaging tire having the pulley contacting surface curved oppositely to the tension curve as of the saw.

2. An improved band saw having a trans verse tension curve said transverse tension curve terminating inwardly of each edge of the saw and merging with an oppositely curved portion adapted to engage the sup porting surface of a wheel to maintain the adjacent edge of the saw free from contact with the wheel.

3. An improved band saw having a circumferential inwardly extending rim engaging tread positioned adjacent each edge and acting to maintain the adjacent edge free from contact with a supporting pulley.

4. An improved band saw having means adjacent each edge extending inwardly from the path of travel of the teeth thereof for contact with a supporting pulley, for the purpose described.

In testimony whereof I hereunto affix my signature.

HUGO PHILLIPS. 

